1. Field of the Invention
The present invention relates to an electrical capacitor, particularly a power capacitor, that is integrated in a metallic housing closed by a moisture tight and gas-tight cover in which at least one electrically-insulating bushing for the capacitor terminals is arranged in the cover.
2. Description of the Prior Art
German application 28 25 377 C2 discloses a capacitor of the type generally set forth above.
An over-pressure can arise in the housing of such a capacitor given an excessively-high heat development in the capacitor winding or, respectively, given the creation of gaseous decomposition products due to self-curing processes in oil-impregnated capacitors. So that this over-pressure does not become excessively great (housing damage, explosion risk), these capacitors have over-pressure break-away fuses that, for example, are composed of rated break locations having cross-sectional diminution arranged in wires or, respectively, leads. Given a deformation of the floor occurring due to elevated internal pressure, the current conductors are torn away via a floor anchoring and, therefore, the power supply is interrupted.
Due to the folded connection between the cover and the housing, the cover, together with the bushings soldered thereinto, must be fabricated of about the same material thickness as the housing. Added thereto is that a non-magnetic, solderable material (for example brass, tinned) that has less strength than steel must be employed because of the bushings (ceramic insulators) to be soldered in as well as because of the alternating fields effective in this region. Due to these restrictions in the thickness of the material and in the type of material, a pronounced deformation of the cover occurs before the shut-off pressure is reached. Since, however, the distance between the bushings changes to an inadmissibly great degree simultaneously with the cover deformation given, for example, two bushings or, respectively, a bushing which can place itself at an angle given only one bushing, the cover must be significantly reinforced.
Ribs in a great variety of shapes, sizes and arrangements have therefore been impressed in the cover for stiffening purposes. The reduction in deformations thereby achieved were nonetheless unsatisfactory or, respectively, inadequate.